Bar code symbology capable of encoding bytes, words, 16-bit characters, etc. and method and apparatus for printing and reading same

ABSTRACT

A new bar code symbology in an exemplary embodiment employs three bars (and spaces) within nine modules, similar to Code 93. Fifty-three data characters are defined, including several special mode characters. By employing these special mode characters, together with certain routines, three symbol characters can represent two 8-bit bytes, or one 16-bit word. As a result, the symbology can efficiently encode 8-bit bytes for use in computer processing, or encode 16-bit character sets such as Unicode. Symbology encodes extended channel interpretation (ECI) numbers, provides multiple numeric compression modes, provides a structured append using a single mode character, as well as other features.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.08/701,304, filed Aug. 21, 1996 now U.S. Pat. No. 5,811,781, which is acontinuation part of application Ser. No. 08/295,382, filed Aug. 24,1994, now U.S. Pat. No. 5,557,092, which is a continuation-in-part ofapplication Ser. No. 08/147,376, filed Nov. 5, 1993, now abandoned.

TECHNICAL FIELD

This invention relates to a new machine-readable symbology, and devicesand methods for reading or printing bar code symbols under thesymbology.

BACKGROUND OF THE INVENTION

Bar code symbologies were first disclosed in U.S. Pat. No. 1,985,035 byKermode and expanded shortly thereafter in the 1930's in U.S. Pat. No.2,020,925 by Young, assigned to Westinghouse. These early symbologieswere printed by generating a multiplicity of single width elements oflower reflectance, or "bars," which were separated by elements of higherreflectance, or "spaces." An "element" is a bar or space. These earlysymbologies, and many "bar code symbologies" used today can be referredto as "linear symbologies" because data in a given symbol is decodedalong one axis or direction. Symbologies such as linear symbologiesencode "data characters" (e.g., human readable characters) as "symbolcharacters," which are generally parallel arrangements of alternatingbars and spaces that form unique groups of patterns to encode specificdata characters. "Data characters" include not only human readablecharacters, but also include special function characters such as start,stop or shift characters that provide certain functional data. Eachunique group or pattern of bars and spaces within a predetermined widthdefines a particular symbol character, and thus a particular datacharacter or characters.

The known U.P.C. symbology can be described generically as a (7,2) "n,kcode." An "n,k code" is defined as a symbology where each symbolcharacter has "k" number of bars and spaces and whose total length is"n" modules long. Therefore, the U.P.C. symbology encodes two bars andtwo spaces in each symbol character and each symbol character is sevenmodules long. A "module" is the narrowest nominal width unit of measurein a bar code symbology (a one-wide bar or space). "Nominal" refers tothe intended value of a specific parameter, regardless of printingerrors, etc. Under common counting techniques, the number of possiblesymbol characters can be found by realizing that in seven modules, thereare six locations where a transition can occur, and that for two barsand two spaces, there are three internal transitions. Therefore, thenumber of unique symbol characters for the U.P.C. symbology is simply 6choose 3 which equals 20. Similarly, under the Code 128 symbology, whichis an (11,3) symbology, 252 unique symbol characters are available (10choose 5).

The bar code symbologies known as U.P.C., EAN, Code 11 and Codabar areall bar code symbology standards which support only numeric datacharacters, and a few special characters such as "+" and "-". The U.P.C.symbology is both a bar code standard, as well as an industry standard,in that it has been adopted by industry in a standard application(consumer goods). The bar code standard Code 39 was the firstalphanumeric bar code symbology standard developed. However, it waslimited to 43 characters.

Code 93 is an improvement over Code 39. Code 93 is a continuous bar codesymbology employing four element widths. Each Code 93 symbol has ninemodules that may be either black or white (either a bar or a space).Each symbol in the Code 93 standard contains three bars and three spaces(six elements), whose total length is nine modules long. Code 93, havingnine modules and three bars per symbol is thus a (9,3) symbology whichhas 56 possible characters (8 choose 5). For edge to edge decodingreasons, the Code 93 symbology standard defines only 48 unique symbols,and thus is able to define 47 characters in its character set plus astart/stop code. The 47 characters include the numeric characters 0-9,the alphabetic characters A-Z, some additional symbols and four shiftcodes.

The computer industry uses its own character encoding standards, namely,the American Standard Code for Information Interchange (ASCII). ASCIIdefines a character set containing 128 characters and symbols. Eachcharacter in ASCII is represented by a unique 7-bit code. Since Code 39and Code 93 are limited to fewer than 50 characters, these standards areinadequate to uniquely represent each ASCII character. The four shiftcodes in Code 93, however, allow this standard to unambiguouslyrepresent all 128 ASCII characters. One drawback is that a series of twoCode 93 symbols are required to represent a single ASCII character.Thus, bar code labels representing characters in the ASCII character setare twice as long as labels representing characters in the Code 93character set.

New bar code symbology standards, such as Code 128, were developed toencode the complete ASCII character set, however, these standards sufferfrom certain shortcomings, including requiring shift codes or otherpreceding symbols to represent certain characters. All of thesesymbologies require increased processing time and overhead to processthe entire ASCII character set.

The computer industry has grown beyond the limits of the ASCII characterset. As the computer markets have grown, the need has also arisen tosupport additional languages not defined by the ASCII character set. Newcharacter sets were developed to accommodate clusters of characters inrelated languages. The original 7-bit ASCII character set was expandedto 8 bits thus providing an additional 128 characters or data values.This additional 128 set of data values (the "upper 128" or "extendedASCII") allowed for additional characters present in the related romancelanguages (i.e., French, German, Spanish, etc.) to be represented. Theonly linear symbologies capable of encoding 8-bit data are Code 128, and"Code 53", which is described in the inventor's U.S. Pat. No. 5,619,027,entitled "Single Width Bar Code Symbology With Full Character SetUtilizing Robust Start/Stop Characters and Error Detection Scheme." BothCode 128 and Code 53 encode 8-bit data by using single or doublefunction shift characters, and thus require increased processing timeand overhead, since every byte value must be analyzed before a datacharacter is encoded.

As the computer markets grew internationally, however, even morelanguages were required to be included in the character set.Particularly, the Asian markets demanded a character set, usable oncomputers, which supported thousands of unique characters. To uniquelydefine each of these characters, a 16-bit encoding standard wasrequired.

Several 16-bit encoding standards such as Unicode, JISC-6226-1983, andothers have recently been developed. The Unicode character encodingstandard is a fixed-length, uniform text and character encodingstandard. The Unicode standard may contain up to 65,536 characters, andcurrently contains over 28,000 characters mapping onto the world'sscripts, including Greek, Hebrew, Latin, Japanese, Chinese, Korean, andTaiwanese. The Unicode standard is modeled on the ASCII character set.Unicode character codes are consistently 16 bits long, regardless oflanguage, so no escape sequence or control code is required to specifyany character in any language. Unicode character encoding treatssymbols, alphabetic characters, and ideographic characters identically,so that they can be used in various computer applications simultaneouslyand with equal facility. Computer programs using Unicode characterencoding to represent characters, but which do not display or printtext, can remain unaltered when new scripts or characters areintroduced.

New computer operating systems are beginning to support thesecomprehensive 16-bit code standards, e.g., WINDOWS NT, manufactured byMicrosoft Corporation of Redmond, Wash. The data collection industry,however, has failed to keep pace with the computer industry. No systemcurrently exists for readily encoding the 16-bit computer charactercodes into bar code symbols. Therefore, there is a need to support these16-bit computer character standards in the data collection industry,particularly for bar code symbologies.

Furthermore, most alphanumeric bar code symbologies are inefficient whenused to encode a long series of numbers. When encoding a series ofdecimal numbers using Code 93 for example, the 26 bar code symbolsreflecting the 26 alphabetic characters are not used. Therefore, thereis a need to allow these alphanumeric bar code symbologies to moreefficiently represent a long series of numbers.

SUMMARY OF THE INVENTION

The present invention solves the above problems and provides additionalbenefits. Under one embodiment of the present invention, a new linearsymbology avoids complex methods of encoding 8-bit and 16-bit data bydescribing a simple byte encodation mode which works on any byte valueuniformly. Under the exemplary embodiment, the present symbology issimilar to the Code 93 symbology, and thus symbol characters are onlynine modules long. Three symbol characters encode two 8-bit bytes. Thus,a byte requires approximately 13.5 modules, regardless of the bytevalue. Further reduction in the number of modules to encode datacharacters are permitted under the exemplary symbology, such as stringsof digits or base Code 93 data characters.

Under an embodiment of the present invention, extended channelinterpretation (ECI) numbers are officially encoded. As a result, a hostcomputer system to which a reader can be coupled can uniquely decode thecoded messages anywhere in the world regardless of the underlyingcharacter sets or applications employed by the host computer.Sixteen-bit characters are represented by three characters under theexemplary symbology, while in another mode, two 8-bit bytes arerepresented by three symbol characters. By representing two 8-bit byteswithin three symbol characters, extended ASCII data characters can beofficially encoded, as well as other relatively small internationalcharacter sets, such as the ISO series 8859-1-8859-9.

In a broad sense, the present invention embodies a method of convertingdata characters to machine-readable symbols, where each symbol has apattern of dark shapes and light spaces between the shapes. The methodincludes the steps of: (a) determining a plurality of character codescorresponding to a plurality of data characters, respectively, whereineach character code has 8 bits; (b) converting the plurality ofcharacter codes to a plurality of symbol values, wherein each of theplurality of symbol values are selected from a set of less than 256symbol values; and (c) printing a plurality of symbols, wherein theplurality of symbols correspond to the plurality of symbol values,respectively.

The present invention also embodies a bar code structure comprising aplurality of adjacently positioned bars having spaces between the bars,groups of at least three bars and three spaces defining one of at least54 individual data characters, each group having at least three bars andthree spaces selected from a plurality of different widths that areinteger multiples of first and second widths, respectively, where eachgroup has a total width substantially equal to at least nine times thefirst or second width.

Furthermore, the present invention embodies a method of converting datacharacters to machine-readable symbols, where each symbol has a patternof dark shapes and light spaces between the shapes. The method includesthe steps of: (a) selecting a group of symbol values consisting of atleast two symbol values; (b) selecting first or second symbol values,wherein the first symbol value indicates that the group of symbol valuestogether correspond to a first mode, and wherein the second symbol valueindicates that the group of symbol values together correspond to asecond mode; and (c) printing a plurality of symbols, wherein theplurality of symbols correspond to the group of symbol values and thefirst or second value. The present invention also includes a method thatincludes the steps of: (a) selecting a group of symbol values consistingof at least two symbol values; (b) providing first and second symbolvalues, wherein the first symbol value indicates that the group ofsymbol values correspond to a portion of a two-dimensional symbol, andwherein the second symbol value indicates a selected position of thegroup of symbol values within the two-dimensional symbol; and (c)printing a plurality of symbols wherein the plurality of symbolscorrespond to the group of symbol values and a first and second symbolvalues.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example of a label having bar code symbol characters, withhuman readable characters, printed or read under an exemplary embodimentof the present invention.

FIG. 2 is a table showing symbol values and associated symbol charactersand data characters for an exemplary symbology under the presentinvention.

FIG. 3 shows an exemplary symbol character format.

FIG. 4 shows the bar code symbol of FIG. 1, with each symbol characteridentified with its associated data character.

FIG. 5 is a table showing full ASCII data characters encodable undersymbology of FIG. 2.

FIG. 6 is a block diagram of a bar code symbol printing apparatus of thepresent invention.

FIG. 7 is an exemplary flow chart showing the basic steps performed bythe printing apparatus of FIG. 6 for printing bar code symbols under theexemplary embodiment.

FIG. 8 is a block diagram of a bar code symbol reading apparatus of thepresent invention.

FIG. 9 is a flow chart showing the basic steps performed by the readingapparatus of FIG. 8 for reading bar code symbols under the exemplaryembodiment.

DETAILED DESCRIPTION OF THE INVENTION

As used generally herein, the following definitions apply: "datacharacters" refers to human readable characters, including symbols,numeric characters, alphabetic characters, and ideographic characters,as well as non-readable data, such as function codes, shift codes, etc.;"numeric string" refers to a sequence of numeric characters, typicallydecimal digits; "character codes" refers to a code, typically numeric,which refers to a data character within a set of character codes andcorresponding data characters, such as ASCII, where "8-bit code" refersto an extended ASCII code corresponding to a data character in the ASCIIstandard, and "16-bit code" or "16-bit character code" refers to ahexadecimal or decimal representation of a data character in a 16-bitcharacter encoding standard, such as Unicode; "bar code symbology"refers to a set of machine-readable or symbol characters for uniquelyrepresenting a set of data characters; "symbol value" refers to a codesuch as an ordinal number representing a data character in a bar codesymbology; "symbol character" refers to the unique geometric shapes orbar and space patterns used in a bar code symbology to representparticular data characters; "bar code standards" refers to a bar codesymbology recognized by, or regularly used in, data collectionapplications (e.g., Code 128, Code 93); and, "counts" refers to a uniqueset of electrical signals produced when reading a symbol charactercorresponding to a data character in a bar code symbology.

For example, in the 16-bit character encoding standard Unicode, the datacharacter "A" is represented by the 16-bit code "0041" in hexadecimalnotation and "65" in decimal. The data character "A" has a symbol valueof "10" in the bar code symbology Code 93. The symbol value 10 in Code93 corresponds to a symbol character having a pattern of a two modulewidth bar followed by: a single module width space, a single modulewidth bar, a single module width space, a single module width bar, and athree module width space. The counts associated with the printing ofthis symbol are generally unique to each printer, and for a thermalprinter, would represent the time intervals between transitions betweenbars and spaces to appropriately activate the printer's heating elementas the thermal sensitive paper moved past it where the bars arepositioned perpendicular to the direction of the label through theprinter. Alternatively, the counts can indicate which dots orthermal-print elements to activate when the bars are parallel with thedirection of the label through the printer.

A new bar code or linear symbology under an embodiment of the presentinvention, generally referred to herein as ",93i" efficiently encodesbytes and words of data, to uniquely represent each 16-bit code in any16-bit character code, encode ECI characters, as well as provideadditional features described in detail herein. FIG. 1 shows an exampleof a label 101 printed or read under the 93i symbology. As shown in FIG.1, the label 101 includes a series of bar code symbols which encode datacharacters, as well as corresponding human readable characters printedthereunder.

The 93i symbology is similar to Code 93. As a result, the 93i symbologyencodes numeric, alpha-numeric, and the full 128 ASCII characters.Additionally, the 93i symbology encodes the extended ASCII charactersand all international character sets, such as those represented by16-bit character codes. The 93i symbology is continuous and employs asymbol structure, as described below, having six elements per symbol,with three bars and three spaces. Characters under the 93i symbology arenot self-checking and symbol length is variable. The 93i symbologyemploys two mandatory symbol check characters. The 93i symbology employsthe equivalent of 37 modules as non-data overhead. Importantly, the 93isymbology permits data character density as follows: 5.4 modules pernumeric digit, 9 modules per symbol character for alpha-numeric data,13.5 modules for lull ASCII and extended ASCII (as defined under theISO8859 8-bit single-byte coded graphic character set standard), and 27modules per Asian or 16-bit character code characters. Additionally, thepresent symbology supports the Extended Channel Interpretation (ECI)protocol (described below), and is fully compatible with the existingCode 93 symbology.

FIG. 2 shows the symbol character assignments for each data character inthe 93i symbology. The "value" column in FIG. 2 represents the symbolvalue for each symbol character. As described herein, the symbol valueis used to compute not only check characters, but is also employed invarious data compression methods. The "character" column in FIG. 2 liststhe alternating bar and space pattern for each symbol character, where a"1" corresponds to one module, "2" corresponds to two modules, etc. Eachcharacter begins with a bar. The "data" column in FIG. 2 represents abase data character corresponding to each symbol character, or thefunctionality of the symbol character. As shown in FIG. 2, symbol values00-46, and their corresponding symbol characters and data charactersmatch the corresponding symbol values, symbol characters, and datacharacters in the Code 93 symbology, as well as the start and stopsymbol characters.

Unlike the Code 93 symbology, the 93i symbology employs 53 symbolvalues, rather than the 47 employed in the Code 93 symbology.Specifically, the 93i symbology adds symbol values 47-52. The symbolvalues 47-52, and corresponding symbol characters and data charactersprovide important functionality, and are described in detail below.

As shown in FIG. 3, the symbol character structure for each symbolcharacter in the 93i symbology employs 3 bars and 3 spaces in 9 modules.Each bar or space is 1, 2, 3, or 4 modules in width. As in the Code 93symbology, the 93i symbology employs a leading quiet zone (QZ) having aminimum width equal to ten times the X dimension, a start symbolcharacter, one or more symbol characters encoding data characters, twosymbol check characters (referred to as "C" and "K"), a stop symbolcharacter, and a trailing quiet zone. FIG. 4 shows the symbol charactersin the label 101 parsed into individual symbol characters, representedby short vertical lines between each symbol character, together with thecorresponding data character for each symbol character.

As noted above, each 93i symbol contains two check characters thatimmediately precede the stop symbol character. All symbol charactershaving a value of 46 or less under a check algorithm in the 93isymbology employ a modulo 47 sum. However, if any symbol character has avalue of 47 or greater, a modulo 53 sum is employed under the checkalgorithm for all symbol values in the symbol.

As with the Code 93 symbology, the check character "C" is computed basedon the modulo sum of the products of the symbol values, as shown in FIG.2, multiplied by a weighting sequence. The weighting sequence, fromright to left (from the stop symbol character to the start symbolcharacter), starting with the immediately preceding character, are inthe repeating sequence 1,2,3, . . . , 20, 1,2,3, . . . 20, 1,2, . . .The check character "K" is produced based on the modulo sum of theproducts of the symbol values and a different weighting sequence, wherethe weights from right to left, beginning with the check character "C"are in the repeating sequence 1,2,3, . . . 15, 1,2,3, . . . 15, 1,2, . .. . As in the Code 93 symbology, the start and stop symbol charactersare not included in the check character calculations.

For example, considering the symbol of FIG. 4, the data characters are,from left to right, 9,3,i,[ECI 16], [45272]. "[ECI 16]" refers to theECI value 000016, while "{45272}" is the Asian character having the16-bit code 45272 in the Unicode standard (which is pronouncedapproximately as "MA"). As used generally herein, the term "symbol" usedalone refers to a collection of symbol characters, such as those shownin the label 101. The numeric data characters "9" and "3" are encodeddirectly, while the data character "i" must be encoded with a shiftcharacter (as described below). As used generally herein, the term"character" used alone refers to either a data character or itscorresponding symbol value. The [ECI 16] data character is formed withtwo symbol characters, while the Asian character {45272} employs a WordMode discussed below. Briefly, the value 45272 is encoded under theformula (24*43²)+(20*43)+36. As a result, the symbol values for theresulting string of symbol characters for encoding the data is:[09][03][46][18][47][16][50][24][20][36]. Employing the above checkcharacter algorithm, with appropriate weighting, the calculation for thecheck character "C" from right to left is as follows. ##EQU1##Similarly, the check character "K" is calculated from a weighting whichincludes "C": ##EQU2##

As noted above, the 93i symbology employs several special characters. Aswith the Code 93 symbology, the 93i symbology employs four shiftcharacters [S1]-[S4], having symbol values 43-46, shown in FIG. 2. Ashift character preceding a symbol value 10-35 represents a single fullASCII data character, as shown in the table of FIG. 5. The charactercombinations [S3]A through [S3]Z in the second column of FIG. 5 arevalid and may be used under the 93i symbology to produce the ASCIIcharacters associated with the single characters indicated. For example,the data character "Q" can be represented by the single symbol value[81] or by the two symbol values [S3][81]. The character pairs [S2] witheither X, Y, or Z all encode the ASCII value DEL (delete).

The 93i symbology employs an ECI character [47], having a symbol value47, that encodes information regarding prescribed meanings of bytes orsubsequent data in a given symbol. The AIMI ECI Assignments documentassigns ECI numbers and the meaning of bytes or data based on the ECInumbers. ECI numbers range from 000000 to 999999. For example, one ECInumber represents the encoding of international character sets. The 93isymbology encodes ECI numbers by placing the ECI number anywhere withina symbol and following it by 1, 2, 3, or 4 symbol values selected fromany of the 53 symbol values of FIG. 2.

A backslash character "\" (reverse solidus), having ASCII value 92 (seeFIG. 5), is transmitted before the six digit ECI value. The backslashcharacter behaves as an escape character to a host computer or systemreceiving the string of symbol values or data produced when a symbol isread. If a backslash character is to be placed within the encoded data,two backslash characters must be encoded within the symbol so that thehost knows that a single backslash character is desired, rather than anECI value. Likewise, if two backslash characters are desired, fourbackslash characters must be encoded for the host to know that twobackslash characters are desired. The rules for encoding ECI numbersunder the 93i symbology are presented below in Table 1.

Summarizing, for ECI numbers 0-899, bytes or data following such numbersare encoded directly even if the data could be compressible otherwise.For example, an ECI number 89 can represent the beginning of aparticular type of encrypted data. The encrypted data which followsthereafter, while compressible, is encoded directly. However, if digitsor full ASCII characters are encoded after an ECI number between 0-899,the Numeric Mode or Byte Mode (described below) can be used to therebyemploy the lower 128 ASCII values and corresponding symbol values asshown in FIG. 5. If ECI numbers are encoded within a string of datacharacters, which are encoded under the Word Mode (described below),then the full 128 ASCII values are employed with eight zeros prependedthereto. ECI numbers 900-999,999 are encoded as bytes in their mostefficient mode, and the Word Mode character ([50]) is prohibited. Forinstance, for ECI number 950, if strings of 93i symbol values 0-9 needto be encoded, the Numeric Mode is employed, even though the values ofthe data characters may not correspond to the numbers employed under themode specified by ECI 950.

Table 1 below summarizes rules for encoding ECI values under the 93isymbology. In Table 1 below, "div" refers to the integer divisionoperator, while "mod" refers to the modulo division operator. "C1"refers to the most significant position, while "C4" refers to the leastsignificant position.

                  TABLE 1                                                         ______________________________________                                        ECI                                                                           Value  Chars.  Value               Range                                      ______________________________________                                        000000-                                                                              C1      ECI.sub.-- val      C1 = 0 to 43                               000043                                                                        000044-                                                                              C1      44                  C1 = 44                                    000096 C2      ECI.sub.-- val - 44 C2 = 0 to 52                               000097-                                                                              C1      45                  C1 = 45                                    002905 C2      (ECI.sub.-- val - 97)div 53                                                                       C2 = 0 to 52                                      C3      (ECI.sub.-- val - 97)mod 53                                                                       C3 = 0 to 52                               002906-                                                                              C1      ((ECI.sub.-- val - 2906)div 148877) + 46                                                          C1 =                                       999999                             46 to 52                                          C2      ((ECI.sub.-- val - 2906)div 2809)mod 53                                                           C2 = 0 to 52                                      C3      ((ECI.sub.-- val - 2906)div 53) mod 53                                                            C3 = 0 to 52                                      C4      (ECI.sub.-- val - 2906)mod 53                                                                     C4 = 0 to 52                               ______________________________________                                    

For example, to encode an ECI value of 000020, the following twocharacter strings are used: [47][20] where [47] is the ECI symbol value47, and [20] is the 93i character "K".

To encode an ECI value of 002000, the following steps are followed toobtain the three required characters:

    ______________________________________                                        [47][45)[(ECI.sub.-- val - 97)div 53][(ECI.sub.-- val - 97)mod 53]=           [47][45][1903 div 53][1903 mod 53]=                                           [47][45][35)[48]                                                              ______________________________________                                    

Finally, to encode an ECI value of 200000, the following steps arefollowed to obtain the four required characters:

    ______________________________________                                        [47][(ECI.sub.-- val - 2906)div 148877 + 46][((ECI.sub.-- val - 2906)div      2809)                                                                         mod 53][((ECI.sub.-- val - 2906)div 53) mod 53][(ECI.sub.-- val -             2906)mod 53]=                                                                 [47][197094 div 148877 + 46][197094 div 2809 mod 53][197094                   div 53 mod 53][197094 mod 53]=                                                [47][1 + 46][70 mod 53][3718 mod 53][40]=                                     [47][47][17][08][40]                                                          ______________________________________                                    

Symbol value 48 represents a numeric compaction mode in the Code 93symbology, referred to herein as "Numeric Mode." Under the Numeric Mode,five numeric digits are compressed into three symbol characters. Thus,sequences of five or more digits should be compressed using the 5/3Numeric Mode. The Numeric Mode character, symbol value 48, toggles intoand out of the 5/3 numeric compression mode. Likewise, the Byte Mode andWord Mode characters, symbol values 49 and 50 respectively, can be usedto exit from the Numeric Mode also. If a symbol ends while in NumericMode, Numeric Mode exiting character is unnecessary.

Under the Numeric Mode, five numeric digits are represented by threesymbol characters, where the symbol characters each have a symbol valuewithin the range of 0-47. The five digit numeric string is produced bythe equation

    A*48.sup.2 +B*48+C                                         (1)

where A, B and C are 93i symbol values. When a string of digits isencoded which is greater than five, but not an exact multiple of five,the following four rules should apply. First, one digit more than amultiple of five in a string is directly encoded by a single symbolcharacter (symbol values 00-09). Second, if the numeric string containstwo more digits than a multiple of five, the last seven digits areseparated into a set of four digits followed by a set of three digits,which are each represented as described by the third and fourth rulesbelow. Third, if a numeric string contains three digits more than amultiple of five, the three digits at the end of the string arerepresented by two symbol characters according to the equation

    48*A+B                                                     (2)

again, where A and B are 93i symbol values. Fourth, if a numeric stringcontains four digits more than a multiple of five, the last four digitsare encoded in three symbol characters under equation (1) above, wherethe resulting value under equation (1) is between 100,000 and 109,999.Table 2 below shows exemplary 5, 6, 7, 8 and 9 digit strings, rangingfrom 12345 to 123456789, and resulting optimal symbol values determinedunder the Numeric Mode.

                  TABLE 2                                                         ______________________________________                                        Exemplary        Optimal Resulting                                            Data             Symbol values                                                ______________________________________                                        12345            [05][17][09]                                                 123456           [05][17][09][06]                                             1234567          [43][45][02][11][39]                                         12345678         [05][17][09][14][06]                                         123456789        [05][17][09][46][16][37]                                     ______________________________________                                    

The ECI value is used as part of the Numeric Mode, where the symbolvalue [47] does not invoke the ECI protocol, but instead is itself usedin the 5/3 numeric compression method. If the ECI value [47] follows astring of digits encoded under the Numeric Mode, the Numeric Mode mustfirst be exited before the ECI value is used.

Symbol value 49 represents a byte mode in the 93i symbology, referred toherein as "Byte Mode." Under Byte Mode, the 93i symbology efficientlyencodes strings of full or extended ASCII data or straight byte data. A"byte" typically refers to an 8-bit set of data. Under the followingequation (3), a double-byte, or two 8-bit bytes, are encoded for each ofthree symbol characters:

    A*43.sup.2 +B*43+C                                         (3)

where A, B, and C are 93i symbol values between 0 and 42.

Under equation (3) two bytes having a combined value between 0 and65,535 are encoded as two symbol characters (i.e., 2¹⁶ =65,536). Valuesresulting from equation (3) between 65,536 to 75,535 encode four digits,while values 75,535 to 76,535 encode three digits. As a result, the ByteMode provides a 3- and 4-digit numeric compaction method to improve theinformation density for encoding strings of numeric characters while inByte Mode. Values resulting from equation (3) between 76,536 and 79,506are not defined, and cause a reader to fail a decode and output an errorsignal.

As with the Numeric Mode, Byte Mode is entered and exited using the ByteMode symbol character, having symbol value 49. The Byte Mode can also beexited by employing the Word Mode symbol character (symbol value 50) orthe Numeric Mode symbol character (symbol value 48). Additionally, ashift character [S1]-[S4], having symbol values 43-46, causes a readerto exit Byte Mode and adds 128 to symbol values for the followingcharacters. Thus, extended ASCII characters can be efficiently encodedafter exiting Byte Mode. Similarly, if one character remains at the endof a symbol, while the preceding characters are in Byte Mode, the finalcharacter is decoded at its symbol value plus 128 (as if in extendedASCII). If a symbol ends while in Byte Mode, an exiting mode character,such as a final Byte Mode symbol character (symbol value 49) isunnecessary. If two characters remain at the end of the symbol, the twocharacters are decoded at their base symbol values, as if Byte Mode hadbeen exited.

Several encoding strategies for improving symbol character encodingefficiency are permitted under the 93i symbology when in Byte Mode. Forexample, Byte Mode permits two extended ASCII data characters to beencoded as a single group of three symbol characters. For even numbersof full or extended ASCII data characters that end with an extendedASCII data character, groups of three symbol characters are employedunder Byte Mode in the 93i symbology. For odd numbers of mixed full andextended ASCII data characters ending with an extended ASCII datacharacter, the even number of characters are represented by groups ofthree symbol characters, and the last (or only) data character isencoded in one of two ways. First, if the last symbol character is anextended ASCII character, then it is encoded as a full ASCII characterpreceded by an appropriate shift character under FIG. 5. Second, if thelast character is a single full ASCII character, then it is encodeddirectly and followed by the Byte Mode character. In both cases, thelast character has a symbol value of 128 plus the value of the basecharacter or shift character (symbol value 00-46, as shown in FIG. 2).

Table 3 below presents optimal encoding of various strings of datacharacters under the Byte Mode. Recall, symbol value [49] refers to theByte Mode character, while [S] represents one of the four shiftcharacters, having symbol values 43-46. In the third column of Table 3below, characters "A" through "F" refer to any data character, havingsymbol values 00-42 in FIG. 2.

                  TABLE 3                                                         ______________________________________                                        No.                                                                           Chars.                                                                              Data Character Type                                                                              93i Character String                                 ______________________________________                                        1     Standard           A                                                    1     Full ASCII         [S]A                                                 1     Extended ASCII     [49][S]A or [49]A[49]                                                         depending on value                                   2     Extended ASCII - then exit                                                                       [49]ABC[49]                                          3     Full/Extended then Extended-exit                                                                 [49]ABC [S]A or                                                               [49]ABC A[49]                                        4     "                  [49]ABC DEF[49]                                      5     "                  [49]ABC DEF [S]A or                                                           [49]ABC DEF A[49]                                    .     .                  .                                                    .     .                  .                                                    .     .                  .                                                    ______________________________________                                    

When strings of numeric data characters are to be encoded between fullor ended ASCII data characters, additional encoding strategies areavailable under the 93i symbology to improve symbol character densities.If one or two numeric data characters are encoded between full orextended ASCII characters, then the one or two numeric characters aretreated as single full ASCII characters, having ASCII values 48 to 57 asshown in FIG. 5, depending upon the number of digits. If three to ninenumeric data characters are encoded between full and extended ASCIIcharacters, then groups of three and four digits are compressed undervalues 65536-75535 and 75536-76535 of 76535 the Byte Mode. In otherwords, the Byte Mode provides satisfactory numeric compression for 3 to9 digit numeric strings within strings of full or extended ASCIIcharacters. However, with a string of 10 digits or more, the Byte Modeshould be exited and the Numeric Mode entered by simply providing theNumeric Mode character [49] thin the string of full or extended ASCIIcharacters.

If one, two, three or four standard or base 93i data characters are tobe encoded within a string of full or extended ASCII characters, thensuch base data characters are treated as bytes. However, if five or morebase data characters are to be encoded within the middle of full orextended ASCII characters, then it is more efficient to shift out ofByte Mode by first encoding the Byte Mode character [49], directlyencode the five or more base data characters, and then reenter the ByteMode with another Byte Mode character [49]. Table 4 below providesexamples of strings of digits placed within strings of full or extendedASCII characters. In Table 4 below, the character types are separated byhyphens.

                  TABLE 4                                                         ______________________________________                                        Data Character Number & Type                                                                  93i Character String                                          ______________________________________                                        2 Extended/Full - 1 digit/Base -                                                              [49]ABC DEF[49]                                               1 Extended                                                                    2 Extended/Full - 1 digit/Base -                                                              [49]ABC DEF [S]A or A[49]                                     2 Extended                                                                    2 Extended/Full - 2 digits/Base -                                                             [49]ABC DEF [S]A or A[49]                                     1 Extended                                                                    2 Extended/Full - 2, 3, 4 digits/                                                             [49]ABC DEF GHI[49]                                           Standard - 2 Extended                                                         .               .                                                             .               .                                                             .               .                                                             2 Extended/Full - 10 digits -                                                                 [49]ABC[48]DEF GHI[49]JKL[49]                                 2 Extended                                                                    2 Extended/Full - 5 Base -                                                                    [49]ABC[49]DEFGH[49]JKL[49]                                   2 Extended                                                                    ______________________________________                                    

Symbol value 50 represents a word mode in the 93i symbology, referred toherein as "Word Mode." Under the Word Mode, three symbol characters aregrouped so that their corresponding three symbol values encode a single16-bit value. Thus, three symbol characters can encode Asian charactersor 16-bit character codes. Character codes up to 65,536 are encodedunder equation (3) above.

Exiting from the Word Mode is performed with either the Word Modecharacter [50], the Byte Mode character [49], or the Numeric Modecharacter [48]. Additionally, as with the Byte Mode, a shift character[S1]-[S4], followed by a single base character, or a single symbolcharacter and the Word Mode character exit from the Word Mode and add128 to the values of single characters. If the symbol ends while in WordMode, an exit character is unnecessary. Where immediately precedingsymbol characters were encoded under the Word Mode, two symbolcharacters at the end of a symbol are decoded at their base value. Ifthe host employs an 8-bit processing architecture, then the reader inByte Mode transmits two consecutive bytes. If the host, however, employs16-bit architecture (e.g., double-bytes processed in parallel), then thereader can employ Word Mode to transmit a single double-byte word of 16bytes to the host.

Again, several strategies for increasing encoding efficiency arepermitted in the 93i symbology when in Word Mode. For example, numericstrings enclosed within characters encoded under the Word Mode arehandled in a manner similar to the Byte Mode described above, exceptstrings having value 76,536 to 76,635 encode two digits. If a singledigit is enclosed within Word Mode characters, the single digit isrepresented by [43] N, where [43] is the first shift character S1, and Nis the numeric digit. Two, three or four numeric digits enclosed withinWord Mode characters are simply represented by the appropriate Word Modevalue, in the same way as Byte Mode. With five numeric digits enclosedwithin Word Mode characters, the Word Mode should be exited and theNumeric Mode entered by simply encoding the Numeric Mode character [48].When a single base, full or extended ASCII character is enclosed withinWord Mode characters, the explicit Word Mode character values areemployed to represent the base, extended or full ASCII characters. Iftwo or more full or extended ASCII characters are encoded within WordMode characters, the Word Mode should be exited and the Byte Modeentered by again simply inserting the Byte Mode character [49]. Table 5below presents several examples of encoding strings of digits or otherdata characters efficiently under the 93i symbology under Word Mode. InTable 5 below, the value "25543" and "18776" refer to two differentUnicode 16-bit codes. Character types in the second column are separatedby hyphens.

                  TABLE 5                                                         ______________________________________                                        Values       Type        93i Characters                                       ______________________________________                                        25543        Unicode     [50]ABC[50]                                          25543, 18776 Unicode     [50]ABC DEF[50]                                      25543, 3, 18776                                                                            Unicode-digit-                                                                            [50]ABC [43]3 DEF[50]                                             Unicode                                                          25543, 3.7, 18776                                                                          Unicode-2 dig-                                                                            [50]ABC DEF GHI[50]                                               Unicode                                                          25543, A, 18776                                                                            Unicode-Std/byte-                                                                         [50]ABC DEF GHI[50]                                               Unicode                                                          25543, AB, 18776                                                                           Unicode-2 Std-                                                                            [50]ABC[50]AB[50]                                                             DEF[50]                                                                       Unicode                                              25543, 233, 231, 18776                                                                     Unicode-2 byte-                                                                           [50]ABC[49]ABC[50]                                                            DEF[50]                                                           Unicode                                                          ______________________________________                                    

Any standard 16-bit data character encoding standard can be used by thepresent invention, for example, Unicode, JISC-6226-1983, Big Five (BF),or KSC 5609-1987. The JISC-6226-1983 standard is the Japan IndustrialStandard Character set, mapping the kanji and katakana data charactersinto 16-bit codes. This data character standard is similar to Unicode,which, as noted above, includes the kanji and katakana data characters,among others. However, each data character in the JISC-6226-1983standard is assigned a different 16-bit code for the equivalent datacharacter in the Unicode standard.

Symbol value 51 represents a function 1 (FNC1) character in the 93isymbology. The FNC1 character in the first or second positions in asymbol signifies compliance of that symbol with a particular applicationstandard, as is known by those skilled in relevant art. The FNC1character in the first position automatically invokes the Numeric Mode,as described above. To encode alphabetic characters (e.g., ASCIIcharacters) immediately following the FNC1 character in the firstposition, the Numeric Mode character [48] is required to return to thebase 93i character set of FIG. 2. The FNC1 character in the secondposition indicates that double-bytes are transmitted, as in the WordMode. The FNC1 character in the third or subsequent positionscorresponds to a transmitted group separator (<GS>) character. If theFNC1 character appears within a symbol, while the symbol is in Numeric,Byte or Word Mode, the FNC1 character is interpreted as if the Numeric,Byte or Word Mode ended, a group separator <GS>character was transmittedand then the previous mode is reentered (i.e., Numeric, Byte or WordMode).

If a symbol is printed with a leading space (symbol value 38), then areader stores the read symbol in a buffer, together with subsequentsymbols having leading spaces, until a symbol without a leading space isencountered. At this time, the entire contents of the buffer, i.e., allread symbols in the buffer, are transmitted, as in the Code 93symbology. As a result, a long symbol can be partitioned into severalsmaller symbols, each of the smaller symbols (except the last) having aleading space data character. If a leading space is desired as the firstdata character in a symbol, without invoking this "leading space append"feature, the Byte Mode should be used.

As explained below with respect to an exemplary decoding routine, areader that reads and decodes 93i symbol characters does not transmitthe start or stop characters or check characters. As with the Code 93symbology, all data characters are transmitted, while a character pairbeginning with one of the shift characters [S1]-[S4] causes only thesingle ASCII character in FIG. 5 to be transmitted. Since the 93isymbology can encode Asian and other 16-bit character codes, a readerwill transmit 16-bit words when in Word Mode. When a reader encounters aWord Mode character [50] within a symbol, together with subsequentlyfill or extended ASCII characters, or base 93i data characters, thereader transmits all ASCII values 0-255 as double-bytes, i.e., a firstbyte consisting of 8 zeros, while the second byte represents the encodedASCII data. If a symbol does not use the Word Mode character [50], and areader is not configured to transmit double-bytes, all data charactersin a 93i symbol are read and transmitted as bytes, as under the ByteMode. Thus, use of transmitted data as single bytes automaticallyprovides more efficiently coded and transmission within a reader underthe 93i symbology if the reader employs 8-bit architecture. When the ECIcharacter [47] exists in a symbol, the same procedures are followed aswith the Word Mode character, but only within the ECI data characterthat contains one or more Word Mode characters as described below.

The 93i symbology preferably employs symbology identifiers. Symbologyidentifiers in the 93i symbology are prefixes to transmitted datadepending upon the nature of the data encoded in a symbol. In otherwords, the symbology identifier is a uniform methodology for reportingthe particular symbology read and options to set in the reader, as wellas any other features of the symbology that are encountered within aparticular symbol. The AIM USA Symbology Identifier Guideline describessymbology identifiers in greater detail. Readers can be programmed toadd the symbology identifier prefix to a given data message which istransmitted from the reader. The particular symbology identifier for the93i symbology is the same as the symbology identifier for Code 93, i.e.,"]G." A modifier data character or characters are then added accordingto the following rules presented in Table 6 below.

                  TABLE 6                                                         ______________________________________                                        Mod                                                                           Char.                                                                              Rule                                                                     ______________________________________                                        0    Code 93 symbol decoded, i.e., no data characters                              having symbol values greater than 46 are present in the symbol.          1    93i symbol decoded, single bytes transmitted                                  (Word Mode character not present in the symbol).                         2    FNC1 character in the first position, single bytes transmitted.          3m   FNC1 character in the second position, followed by                            the value of the preceding character, single                                  bytes transmitted.                                                       4    93i symbol decoded, double bytes transmitted, including                       symbology identifiers.                                                   5    FNC1 character in the first position, double bytes transmitted.          6m   FNC1 character in the second position, followed by                            the value of the preceding character, double                                  bytes transmitted.                                                       7    ECI character present, bytes transmitted with                                 "\NNNNNN" ECI value included in                                     the transmission, and encoded "\" characters                        doubled. For ECI values 0-900, double-bytes are transmitted                   within the ECI when a Word Mode character is present,                         and bytes otherwise. For ECI values                                           901-999999, the Word Mode character is not encoded                            and all characters are transmitted as bytes.                             8    ECI character present, all characters are                                     transmitted as double bytes, including the ECI sequence.                 9    FNC1 character in the first position, ECI character                           present and single bytes transmitted.                                    Am   FNC1 character in the second position, followed                               by the value of the preceding character, ECI character present                and single bytes transmitted.                                            B    FNC1 character in the first position, ECI character                           present and double bytes transmitted.                                    Cm   FNC1 character in the second position,                                        followed by the value of the preceding character,                             ECI character present and double bytes                                        transmitted.                                                             ______________________________________                                    

The modifier character "m" corresponds to particular applicationstandard followed and registered with AIM. The modifier character "m"occurs only when the FNC1 character is in the second position.

Symbol value 52 is an unassigned data character. Symbol value 52 couldbe used as a single character flag for multirow ordered concatenation orstructured append. In other words, the unassigned symbol value 52,together with one or more subsequent symbol values, can be employed inseveral separate symbols to designate a complete two-dimensional symbol.For instance, the flag may be followed by a single character whose valueis made up of the position and the size of the symbol. The unassignedcharacter 52, together with the one or more subsequent symbol values,indicate a precise location of each symbol within a two-dimensional areato effectively form a two-dimensional symbol. For example, four symbolscan together form a single two-dimensional symbol having two rows. Theunassigned symbol value 52, together with a first, subsequent symbolvalue, can indicate that one symbol forms the upper-left portion of thetwo-dimensional symbol, while the unassigned symbol with a second symbolvalue indicates that another of the four symbols corresponds to thelower-right corner of the two-dimensional symbol. The check charactersfor the last symbol in the structured append two-dimensional symbol arecheck characters for the entire two-dimensional symbol.

An example of data transmitted from a reader based on the symbol of FIG.1 will now be presented. The symbol of FIG. 1 encodes the string, "9, 3,i, ECI 16, {45272}" and the data transmitted would be:

    ]G7\000003 9 3 i \000016 45272

which in bytes is:

    93, 71, 55, 92, 48, 48, 48, 48, 48, 51, 57, 51, 105, 92, 48, 48, 48, 48, 49, 54, 176, 216.

Note that the symbology identifier "]G7" transmitted initially with thedata includes the modifier character "7" that indicates, under Table 6that an ECI character is present and bytes are transmitted with"\NNNNNN" ECI value included in the transmission. If the reader wereconfigured to transmit all single bytes as double bytes, and double bytecharacters unchanged, the Symbology Identifier would change to "]G8",and the following byte sequence would be transmitted from the reader:

    0, 93, 0, 71, 0, 56, 0, 92, 0, 48, 0, 48, 0, 48, 0, 48, 0, 48, 0, 51, 0, 57, 0, 51, 0, 105, 0, 92, 0, 48, 0, 48, 0, 48, 0, 48, 0, 49, 0, 54, 176, 216.

Because the symbol contains an ECI character, Symbology Identifiers mustbe used, and the reader cannot decode a symbol without transmitting theSymbology Identifier characters. However, if the ECI characters"\000003" and "\000016" were not encoded in the symbol, then it would beup to the host receiving the transmitted data from the reader tointerpret the transmitted message. In that case, where a Word Modecharacter is encoded in the symbol, the reader must transmit the symbolas double bytes, and if Symbology Identifiers were enabled, the correctprefix would be "]G4." Similarly, if a Word Mode character were notpresent in the symbol, but the reader were configured to transmit allsingle bytes as double bytes and all double byte characters unchanged,the Symbology Identifier would still be "]G4". Consequently, an encodestring "9, 3, i, {45272}" would be transmitted as:

    ]G4 9 3 i 45272

which in bytes is:

    0, 93, 0, 71, 0, 52, 0, 57, 0, 51, 0, 105, 176, 216.

FIG. 6 shows an exemplary symbol character printing apparatus 100. Theapparatus 100 consists of a printer 102, a central processing unit (CPU)104, a memory 106, a keyboard 107 and a secondary storage 108. Theprinter 102 is of a type generally known which can print bar codes andhuman readable data characters. Those skilled in the art may select fromany such printers which are suitable for use in the present invention.The CPU 104 is electrically coupled to a host computer, or otherapparatus or applications, by a port or line 109. The CPU 104, executinga routine (FIG. 2) stored in the memory 106 and/or the secondary storage108, converts a 16-bit data character code into counts which are sent tothe printer 102. The printer 102 interprets these counts and convertsthem into printed symbol characters, typically in the form of a bar codelabel. A "label" generally refers to any paper, cloth, plastic, metal orother pliable or rigid material suitable for having one or more symbolcharacters and/or data characters printed or formed thereon. Thoseskilled in the relevant art, however, will recognize that the term"label" also refers to any symbol characters printed on an object, suchas packaging for a consumer product, or relief formed on an object. Theprinted label can include both symbol characters and the correspondinghuman readable data characters. The label 101 of FIG. 1 is an example ofa label printed or read under embodiments of the present invention.

FIG. 7 shows exemplary steps performed by the printing apparatus 100 ofFIG. 6 under a routine 111 for printing a bar code label having multiplesymbol characters and with corresponding data characters. In step 110, astring of data characters are selected, input or determined, forexample, such as input using the keyboard 107. The string of datacharacters may also be input to the CPU 104 over the line 109 from thehost computer 105. When a key is depressed on the keyboard 107, thekeystroke is converted into a "scan code" which is transmitted from thekeyboard to the device to which the keyboard is connected (e.g., theprinting apparatus 100 or the host computer 105). This scan coderepresents the particular key of the keyboard which has been depressed,and is unrelated to any particular character or value in a datacharacter set, such as ASCII or Unicode.

In step 112, the CPU 104 divides or parses the selected characters intovarious sets of data characters, such as alphabetic characters, numericcharacters, 8-bit bytes, 16-bit words or characters, etc. Data parsingtechniques are well known in the relevant art. In step 114, the CPU 104defines any special characters, such as shift characters [S1]-[S4], modecharacters, such as numeric, byte and word mode characters [48], [49] or[50], respectively, etc. Additionally, in step 114, the CPU 104determines whether any ECI numbers are to be encoded in the symbol.

In step 116, the CPU 104 determines an optimized string of symbolcharacters based on the selected data characters. For example, if fiveconsecutive data characters are numeric, then the CPU 104 determinesthat the Numeric Mode should be employed to reduce the number of symbolcharacters and thereby increase information density of the resultingsymbol. CPU 104 in step 116 employs the rules and suggestions presentedabove for increasing information density in a symbol (e.g., as shown inTables 3 and 4).

In step 118, the CPU 104 determines the symbol value for each datacharacter. A table of data characters and their corresponding symbolvalues is preferably stored in the secondary storage 108, along with thecounts for the corresponding symbol characters, such as the tables ofFIGS. 2 and 5. Alternatively, the symbol values can be automaticallycalculated from knowledge of the data characters. The CPU 104 in step118 encodes selected data characters into symbol characters selectedfrom the table of FIG. 2 based on the appropriate routine describedherein. For example, if the CPU 104 encounters a string of three or fivedigits, the CPU employs equations (1) and (2), respectively, which aredescribed above. If bytes are to be encoded, then the CPU 104 employsthe equation (3).

In step 120, the CPU 104 generates the check characters "C" and "K" byemploying the above-described check character algorithm. In step 122,the CPU 104 chooses a suitable X-dimension for the symbol based on, inpart, the number of symbol characters to be printed. In step 124, theCPU 104 chooses other format options, such as printing the symbol withthe human readable data characters, or other format options known bythose skilled in the relevant art. In step 126, the CPU 104 outputs theappropriate codes and other signals to the printer 102, which in turnprints the symbol as a series of symbol characters (and possibly datacharacters) to form the bar code label.

The 93i symbology can also be readily read using a bar code readingapparatus such as a bar code reading apparatus 140, shown in FIG. 8. Thereading apparatus 140 has a standard bar code reader 142. The bar codereader 142 includes an electro-optical device 143 such as a laserscanner, rasterizing laser, or wand-based optical transducer.Alternatively, the electro-optical device 143 in the reader 142 caninclude a one- or two-dimensional CCD, semiconductor array, vidicon, orother area imager capable of converting received light into electricalsignals. The electro-optical device 143 in the reader 142 can alsoinclude a light source such as an LED, flash bulb, infrared lightsource, or other light-emitting element. As used generally herein, theterm "reader" refers to any device capable of converting modulated lightreceived from a bar code into electrical signals. Readers are known bythose skilled in the art, and any such reader suitable for use in thepresent invention can be selected. The data read from the bar codereader 142 is input to a CPU 144. A memory 146 and a secondary storage148 are coupled to the CPU 144. The data input to the bar code reader142 is processed by the CPU 144 and output to a host computer 147, orother apparatus or applications, by a port or line 149.

FIG. 9 shows the steps performed under a routine 150 by the readingapparatus 140 of FIG. 8 for reading bar code symbols having symbolcharacters from the present symbology. In step 151, the bar code reader142 scans or images the symbol characters of a bar code label anddetermines the width of the elements, e.g., by determining a series ofcounts. As is known by those skilled in the art, the transitions betweenbars in the symbol characters, together with a timer within the readingapparatus 140, determine the counts of the symbol characters read. Thecounts in turn are used to determine the widths of elements in a givensymbol. In step 152, the CPU 144 analyzes the counts, to locate thequiet zones on both sides of the symbol.

In step 154, the CPU 144 selects the first 6 counts, which represent thefirst string of 6 element widths. In step 156, the CPU 144 divides thefirst six counts by 9 and normalizes the result to estimate the widthsof the individual elements. In step 158, the CPU 144 compares the widthsof the first 6 elements to the string of widths for the start characterand with the reverse string of widths for the stop character. If thelast 6 elements in the string correspond to the 6 elements from thestart character, but in reverse, the CPU 144 recognizes that the symbolhas been scanned in reverse, and therefore recognizes that the symbol isto be read from right to left (as opposed to the traditional left toright).

In step 160, the CPU 144 selects the next 6 elements, and in step 162,divides the sum of the elements (counts) by 9 and normalizes the result.In step 164, the CPU 144 determines the symbol value for the selected 6elements. In step 166, the CPU 144 determines if the label contains anyadditional elements and if so, loops back to step 160 to perform thesteps 160 through 164 again until all of the symbol characters have beenconverted into symbol values.

In step 168, the CPU 144 determines if any invalid/undecodable symbolcharacters have been generated. If some symbol characters are determinedto be undecodable, then the routine loops back to step 160 and the CPU144 performs other known decode methods, such as edge-to-edge (elementpairs) decoding for individual elements in the symbol. Alternatively, instep 168, the CPU 144 performs bar-to-bar or space-to-space comparisons,or Factor R decoding methods, known to those skilled in the art.

In step 168, the CPU 144 can also verify or determine whether the symbolcharacters are in focus. The CPU 144 analyzes the signals produced bythe bar code reader 142 for the symbol characters to determine whetherthe CPU can recognize the wide elements but fail to recognize theone-wide elements. If the CPU 144 cannot recognize the one-wide elementsin one or more symbol characters, the CPU aborts the decode routine,provides unfocused data to the CPU, or performs other functions such asalerting the user that the symbol is not in focus. If the CPU 144 issufficiently programmed, it can decode the unfocused data based on thepresent inventor's U.S. Pat. Nos. 5,486,689, 5,514,858, 5,539,191 and/orU.S. patent application Ser. No. 08/493,669, filed Oct. 12, 1996.

If the symbol is in focus or if the CPU 144 decodes the unfocused data,so that all of the symbol values are valid (i.e., map to datacharacters) then in step 170, the CPU performs the check calculationbased on the last two symbol characters. If the check characters checkunder the above algorithms, then in step 171, the CPU 144 converts thesymbol values into data characters based on a look-up table, byretrieving the appropriate data characters from the memory 146 or thesecondary storage 148 depending upon where the appropriate data isstored. The data characters can then be displayed, or used in otherapplications by the CPU 144, or output over the line 149 to the hostcomputer 147. In step 171, the CPU 144 also interprets any shift or Modesymbol values, such as symbol values 48-50 for the Numeric, Byte andWord Modes, respectively. When the CPU 44 encounters one of the Modecharacters, or other special characters (symbol values 43-52), the CPUenters the appropriate mode or decodes the symbol values as describedabove. Alternatively, the CPU 144 can simply output the symbol valuesover the line 149 to the host computer 147, which in turn performs theconversion into the corresponding data characters.

Although specific embodiments of, and examples for, the presentinvention have been described above for illustrative purposes, variousequivalent modifications may be made without departing from the spiritand scope of the invention. For example, if the memory 106 or 146 issufficiently large to contain all data required by the CPU 104 or 144for encoding, decoding, printing or reading bar code labels, thesecondary storage 108 or 148 is unnecessary and thus eliminated.Alternatively, the data required by the CPU 104 or 144 may be containedin the secondary storage 108 or 148, thus eliminating the need for alarge memory 106 or 146 or the need for this memory entirely. Regardingthe 93i symbology, the symbol characters can be allocated to differentdata characters than as described above with respect to FIG. 2. Errorcorrection characters can be added to any label to provide the abilityto correct errors in the label. The FNC1 character [51], or theunassigned symbol character [52] can be used to latch into a mode forencoding other sets of data characters. For example, where the Word Modecharacter [50] can be used to encode the Unicode characters, while theunassigned character [52] can latch to encode the JISC-6226-1983characters. Additionally, the present invention can incorporate theteachings of the U.S. Patents and/or applications described herein toprovide additional benefits and functionality. The U.S. Patents andapplications cited above are incorporated herein by reference as if setforth in their entirety.

These and other changes can be made to the invention in light of theabove detailed description. In general, in the following claims, theterms should not be construed to limit the invention to the specificembodiments disclosed in the specification and claims, but should beconstrued to include all apparatus, methods and symbologies for directlyencoding various data characters, such as 8-bit bytes, 16-bit charactercodes, ECI numbers, etc. Accordingly, the invention is not limited bythe disclosure, but instead its scope is to be determined entirely bythe following claims.

I claim:
 1. A method of converting data characters to machine-readablesymbols, each symbol having a pattern of dark shapes and light spacesbetween the shapes, the method comprising:determining first and secondcharacter codes corresponding to first and second data characters,respectively, wherein each character code has 8 bits; converting thefirst and second character codes to first, second and third symbolvalues; and printing first, second, third symbol characters, wherein thefirst, second and third symbol characters correspond to the first,second and third symbol values, respectively.
 2. The method of claim 1wherein printing includes printing first, second and third symbolcharacters selected from a symbology having three shapes and ninemodules per symbol character.
 3. The method of claim 1 whereindetermining, converting and printing are repeated for each pair of datacharacters in a selected string of data characters, and wherein eachdata character has a corresponding 8 bit character code.
 4. The methodof claim 1, further comprising printing an additional symbol character,and wherein the additional symbol character indicates that the first,second and third symbol characters correspond to at least one charactercode having 8 bits.
 5. The method of claim 1, further comprisingprinting an additional symbol character, and wherein the additionalsymbol character indicates that symbol characters correspond to at leastone 16-bit character code selected from the Unicode standard.
 6. Themethod of claim 1, further comprising:selecting a first number ofdigits; converting the number of digits to a second number of symbolvalues, the second number being less than the first number; printing thesecond number of symbol characters corresponding to the symbol values;and printing an additional symbol character, wherein the additionalsymbol character indicates that the second number of symbol characterscorrespond to digits.
 7. The method of claim 1, furthercomprising:selecting a number corresponding to preselected datainterpretable by a computer; converting the number to at least oneselected symbol value; printing at least one selected symbol charactercorresponding to the at least one selected symbol value; and printing anadditional symbol, wherein the additional symbol indicates that the atleast one selected symbol corresponds to one of a plurality ofpredetermined numbers.
 8. The method of claim 1, furthercomprising:employing a first check character mode if any of the first,second and third symbol values have a first range of values; employing asecond check character mode if any of the first, second and third symbolvalues have a second range of values; and computing at least a firstcheck value under the first or second check character modes based on thefirst, second and third symbol values.
 9. The method of claim 1, furthercomprising printing an additional symbol character, wherein theadditional symbol character indicates that at least the first symbolcharacter corresponds to a selected position within a two-dimensionalsymbol.
 10. A method of converting data characters to machine-readablesymbols, each symbol having a pattern of dark shapes and light spacesbetween the shapes, the method comprising:determining a plurality ofcharacter codes corresponding to a plurality of data characters,respectively, wherein each character code has 8 bits; uniformlyconverting the plurality of character codes to a plurality of symbolvalues, wherein each of the plurality of symbol values are selected froma set of less than 256 symbol values; and printing a plurality of symbolcharacters, wherein the plurality of symbols correspond to the pluralityof symbol values, respectively.
 11. The method of claim 10 whereinprinting includes printing a plurality of symbol characters selectedfrom a symbology having three shapes and nine modules per symbolcharacter.
 12. The method of claim 10, further comprising printing anadditional symbol character, wherein the additional symbol characterindicates that the plurality of symbol characters correspond to at leastone 8-bit byte.
 13. The method of claim 10, further comprising printingan additional symbol character, wherein the additional symbol characterindicates that each group of proximate symbol characters correspond toone 16-bit word.
 14. The method of claim 10, furthercomprising:selecting a first number of digits; converting the firstnumber of digits to a second number of symbol values, the second numberbeing less than the first number; printing the second number of symbolcharacters corresponding to the second number of symbol values; andprinting an additional symbol character, wherein the additional symbolcharacter indicates that at least the second number of symbol characterscorrespond to digits.
 15. The method of claim 10, furthercomprising:selecting a number corresponding to preselected datainterpretable by a computer; converting the number to at least oneselected symbol value; printing at least one selected symbol charactercorresponding to the at least one selected symbol value; and printing anadditional symbol, wherein the additional symbol indicates that the atleast one selected symbol corresponds to one of a plurality ofpredetermined numbers.
 16. The method of claim 10, furthercomprising:employing a first check character mode if any of theplurality of symbol values have a first range of values; employing asecond check character mode if any of the plurality of symbol valueshave a second range of values; and computing at least a first checkvalue under the first or second check character modes based on theplurality of symbol values.
 17. The method of claim 10, furthercomprising printing an additional symbol character, wherein theadditional symbol character indicates that the plurality of symbolcharacters correspond to a selected position within a two-dimensionalsymbol.
 18. The method of claim 10 wherein printing includes printingseveral symbols selected from a standard bar code symbology.
 19. A barcode structure comprising a plurality of adjacently positioned barshaving spaces between the bars, groups of at least three bars and threespaces defining one of at least fifty individual data characters, eachgroup having at least three bars and three spaces selected from aplurality of different widths that are integer multiples of first andsecond widths, respectively, wherein each group has a total widthsubstantially equal to 9 times the first or second width.
 20. The barcode structure of claim 19 wherein one of the groups represents a bytemode data character, wherein the byte mode character indicates thatgroups correspond to at least one character code having 8 bits.
 21. Thebar code structure of claim 19 wherein one of the groups represents aword mode data character, wherein the word mode data character indicatesthat groups correspond to at least one 16-bit character code.
 22. Thebar code structure of claim 19 wherein some of the groups aresubstantially identical to groups selected from a symbology standard.23. A method of converting data characters to machine-readable symbols,each symbol having a pattern of dark shapes and light spaces between theshapes, the method comprising:selecting a group of symbol valuesconsisting of at least two symbol values; selecting first or secondsymbol values, wherein the first symbol value indicates that the groupof symbol values together correspond to a first mode and wherein thesecond symbol value indicates that the group of symbol values togethercorrespond to a second mode and printing a plurality of symbols, whereinthe plurality of symbols correspond to the group of symbol values andthe first or second symbol value.
 24. The method according to claim 23wherein selecting a group includes selecting a group of symbol valuescorresponding to a string of digits, and wherein selecting first orsecond symbol values includes selecting first or second numericcompression modes.
 25. The method of claim 23 wherein selecting first orsecond includes selecting a third symbol value, and wherein the thirdsymbol value indicates that the group of symbol values corresponds to atleast one character code having 8 bits.
 26. The method of claim 23wherein selecting first or second includes selecting a third symbolvalue, and wherein the third symbol value indicates that the group ofsymbol values corresponds to at least one 16-bit character code.
 27. Themethod of claim 23 wherein selecting first or second includes selectinga third symbol value, and wherein the third symbol value indicates thatthe group of symbol values corresponds to at least one selected numbercorresponding to preselected data interpretable by a computer.
 28. Themethod of claim 23 wherein selecting first or second includes selectingat least a third symbol value, and wherein the third symbol valueindicates that the group of symbol values correspond to a selectedposition within a two-dimensional symbol.
 29. A method of convertingdata characters to machine-readable symbols, each symbol having apattern of dark shapes and light spaces between the shapes, the methodcomprising:selecting a group of symbol values consisting of at least twosymbol values; providing first and second symbol values, wherein thefirst symbol value indicates that the group of symbol values correspondto a portion of a two-dimensional symbol, and wherein the second symbolvalue indicates a selected position of the group of symbol values withinthe two-dimensional symbol; and printing a plurality of symbols, whereinthe plurality of symbols correspond to the group of symbol values andthe first and second symbol values.
 30. The method of claim 29 whereinselecting a group includes computing at least one check character forthe two dimensional symbol.
 31. A method of decoding a bar code labelformed on a surface, the method comprising:imaging the bar code label toproduce a signal representative of each of a plurality of symbolcharacters therefrom; analyzing the signal to identify the symbolcharacters; and converting each symbol character into a correspondingsymbol value, wherein each of the plurality of symbol values areselected from a set of less than 256 symbol values, and wherein aplurality of symbol values together uniformly represent at least onecharacter code having 8 bits.
 32. A printer apparatus for printingmachine-readable symbols comprising:a processor that uniformly convertsa plurality of character codes to a plurality of symbol values, whereinthe plurality of character codes correspond to a plurality of datacharacters, respectively, wherein each character code has 8 bits, andwherein each of the plurality of symbol values are selected from a setof less than 256 symbol values; and a printer mechanism coupled to theprocessor that prints a plurality of symbol characters, wherein theplurality of symbol characters correspond to the plurality of symbolvalues, respectively.
 33. A reader apparatus for readingmachine-readable symbols comprising:an optical receiver that receiveslight reflected from a plurality of symbols and produces a signalrepresenting the plurality of symbol characters; and a processor coupledto the optical receiver that receives the signal and converts theplurality of symbol characters to a plurality of symbol values, whereineach of the plurality of symbol values are selected from a set of lessthan 256 symbol values, wherein each symbol value corresponds to one ofa plurality of data characters, wherein at least some of the pluralityof data characters uniformly correspond to a plurality of charactercodes, respectively, and wherein each character code has 8 bits.
 34. Amethod of converting data characters to machine-readable symbols, eachsymbol having a pattern of dark shapes and light spaces between theshapes, the method comprising:determining a plurality of character codescorresponding to a plurality of data characters, respectively, whereineach character code has 8 bits; without using shift symbols, convertingthe plurality of character codes to a plurality of symbol values,wherein each of the plurality of symbol values are selected from a setof less than 256 symbol values; and printing a plurality of symbolcharacters, wherein the plurality of symbols correspond to the pluralityof symbol values, respectively.
 35. The method of claim 34 whereinprinting includes the printing a plurality of symbol characters selectedfrom a symbology having three shapes and nine modules per symbolcharacter.
 36. The method of claim 34 further comprising printing anadditional symbol character, wherein the additional symbol characterindicates that the plurality of symbol characters correspond to at leastone 8-bit byte.
 37. The method of claim 34, further comprising printinga additional symbol character, wherein the additional symbol characterindicates that each group of proximate symbol characters correspond toone 16-bit byte.
 38. The method of claim 34, furthercomprising:employing a first check character mode if any of theplurality of symbol values have a first range of values; employing asecond check character mode if any of the plurality of symbol value havea second range of values; and computing at least a first check valueunder the first or second check character modes based on the pluralityof symbols values.
 39. The method of claim 34, further comprisingprinting an additional symbol character, wherein the additional symbolcharacter indicates that the plurality of symbol characters correspondto a selected position within a two-dimensional symbol.
 40. A method ofdecoding a bar code label formed on a surface, the methodcomprising:imaging the bar code label to produce a signal representativeof each of a plurality of symbol characters therefrom, wherein theplurality of symbol characters are selected from a set of symbolcharacters; analyzing the signal to identify the symbol characters; andconverting each symbol character into a corresponding symbol value,wherein each of the plurality of symbol values are selected from a setof less than 256 symbol values corresponding to the set of symbolcharacters, wherein a plurality of symbol values together represent atleast one character code having 8 bits, and wherein the converting isperformed uniformly with respect to the entire set of symbols values.41. The method of claim 40 wherein converting includes converting eachsymbol characters from the set of symbol characters, wherein each symbolcharacters in the set of symbol has three shapes and nine modules persymbols character.
 42. The method of claim 40, furthercomprising:identifying an additional symbol character wherein theadditional symbol character indicates that the plurality of symbolcharacters correspond to at least one 18-bit byte.
 43. The method ofclaim 40, further comprising:identifying an additional symbol character,wherein the additional symbol character indicates that each group ofproximate symbol characters correspond to at least one 16-bit word. 44.A printer apparatus for printing machine-readable symbols comprising:aprocessor that converts a plurality of character codes to a plurality ofsymbol values, wherein the plurality of character codes correspond toplurality of data characters, respectively wherein each character codehas 8 bits, and wherein each of the plurality of symbol values areselected from a set of less than 256 symbol values, and wherein theconverting is performed uniformly with respect to the entire set ofsymbol values; and a printing mechanism coupled to the processor thatprints a plurality of symbols characters, wherein the plurality ofsymbol characters correspond to the plurality of symbols values,respectively.
 45. The printer of claim 44, wherein each of the symbolcharacters is selected from a symbology having three shapes and ninemodules per symbol character.
 46. The printer of claim 44, wherein theprinter prints an additional symbol character, wherein the additionalsymbol character indicates that the plurality of symbol characterscorrespond to at least one 8-bit byte.
 47. The printer of claim 44,wherein the printer mechanism prints an additional symbol character,wherein the additional symbol character indicates that each group ofproximate symbol characters correspond to one 16-bit word.
 48. A readerapparatus for reading machine-readable symbols comprising:an opticalreceiver that receives light reflected from a plurality of symbols andproduces a signal representing the plurality of symbol character,wherein the plurality of symbols are selected from a set of symbols; anda processor coupled to the optical receiver that receives the signal andconverts the plurality of symbol characters to a plurality of symbolvalues, wherein each of the plurality of symbol values are selected froma set of less than 256 symbol values corresponding to the set ofsymbols, wherein each symbols values correspond to one of a plurality ofdata characters, wherein at least some of the plurality of datacharacter correspond to a plurality of character codes, respectively,wherein each character code has 8 bits and wherein the processoruniformly converts all symbol characters in the set of symbols.
 49. Thereader apparatus of claim 48, wherein each plurality of symbolcharacters has three shapes and nine modules per symbols character. 50.The reader apparatus of claim 48, wherein the optical receives lightreflected from an additional symbol character, wherein the additionalsymbol character indicates that the plurality of symbol characterscorrespond to at least one 8-byte.
 51. The reader apparatus of claim 48,wherein the optical receiver receives light from an additional symbolcharacter, wherein the additional symbol character indicates that eachgroup of proximate symbol characters correspond to one 16-word.